1. Field of Invention
This invention relates to wireless communications and more particularly to a method and system for delaying retransmission of data traffic to a wireless terminal.
2. Description of Related Art
A wireless terminal is a form of telecommunications technology that enables people to communicate with others. The wireless terminal can take a variety of forms. The wireless terminal may be, for example, a cellular phone, a pager, a personal digital assistant (PDA), a portable computer with wireless modem, or a fixed wireless terminal.
An air interface separates the wireless terminal from a radio access network. The radio access network facilitates communication over the air interface, as between the wireless terminal and a remote terminal. The communication between the wireless terminal and the remote terminal may take the form of data traffic or voice traffic. The data traffic may represent data, such as session initiation protocol (SIP) messages, SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions) messages, wireless access protocol (WAP) messages, or some other type of messages. The voice traffic, on the other hand, may represent voice communications as produced, for instance, by a voice coder (vocoder).
The radio access network typically has a base station. In at least code division multiple access (CDMA) protocol, the base station assigns to a wireless terminal an air interface traffic channel to convey voice traffic or data traffic. The traffic channel defines a radio link layer connection to convey the voice traffic or the data traffic from the base station to the wireless terminal. Under many existing procedures, if a base station already assigned to a wireless terminal a traffic channel to convey voice traffic, then the base station cannot assign to the wireless terminal a traffic channel to convey data traffic. In CDMA, all traffic channels assigned to convey voice traffic to the wireless terminal would have to be released before the base station could assign a traffic channel to convey data traffic.
A proxy server may be communicatively coupled to the radio access network. The proxy server may enable the wireless terminal and the remote terminal to engage in instant messaging, short mail, or push-to-talk (PTT) communication sessions between the wireless terminal and the remote terminal.
In common with these types of communication sessions and others is that the proxy server has to send to the wireless terminal, data traffic. The proxy server typically sends the data traffic to the base station over the air interface. If the base station assigned to the wireless terminal a traffic channel to convey data traffic, then a radio link layer connection to the wireless terminal is available to convey the data traffic. The base station will send the data traffic to the wireless terminal. In turn, the wireless terminal will receive the data traffic and send an acknowledgement back to the proxy server. The acknowledgment indicates to the proxy server that the wireless terminal received the data traffic.
If, on the other hand, the base station assigned to the wireless terminal a traffic channel to convey voice traffic, then a radio link layer connection to the wireless terminal is unavailable to convey data traffic. The base station will buffer the data traffic. The base station will, for instance, buffer the data traffic in a packet control function (PCF) resident on the base station. When the base station releases all traffic channels assigned to the wireless terminal to convey voice traffic, then the base station may assign a traffic channel to the wireless terminal to convey data traffic. By assigning a traffic channel to convey the data traffic, the base station will be able to send to the wireless terminal the data traffic buffered in the PCF.